/*
** $Id: lstate.c,v 2.99 2012/10/02 17:40:53 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/


#include <stddef.h>
#include <string.h>

#define lstate_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "llex.h"
#include "lmem.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"


#if !defined(LUAI_GCPAUSE)
#define LUAI_GCPAUSE	200  /* 200% */
#endif

#if !defined(LUAI_GCMAJOR)
#define LUAI_GCMAJOR	200  /* 200% */
#endif

#if !defined(LUAI_GCMUL)
#define LUAI_GCMUL	200 /* GC runs 'twice the speed' of memory allocation */
#endif


#define MEMERRMSG	"not enough memory"


/*
** a macro to help the creation of a unique random seed when a state is
** created; the seed is used to randomize hashes.
*/
#if !defined(luai_makeseed)
#include <time.h>
#define luai_makeseed()		cast(unsigned int, time(NULL))
#endif



/*
** thread state + extra space
*/
typedef struct LX {
#if defined(LUAI_EXTRASPACE)
	char buff[LUAI_EXTRASPACE];
#endif
	lua_State l;
} LX;


/*
** Main thread combines a thread state and the global state
*/
typedef struct LG {
	LX l;
	global_State g;
} LG;



#define fromstate(L)	(cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))


/*
** Compute an initial seed as random as possible. In ANSI, rely on
** Address Space Layout Randomization (if present) to increase
** randomness..
*/
#define addbuff(b,p,e) \
{ size_t t = cast(size_t, e); \
	memcpy(buff + p, &t, sizeof(t)); p += sizeof(t); }

static unsigned int makeseed (lua_State *L) {
	char buff[4 * sizeof(size_t)];
	unsigned int h = luai_makeseed();
	int p = 0;
	addbuff(buff, p, L);  /* heap variable */
	addbuff(buff, p, &h);  /* local variable */
	addbuff(buff, p, luaO_nilobject);  /* global variable */
	addbuff(buff, p, &lua_newstate);  /* public function */
	lua_assert(p == sizeof(buff));
	return luaS_hash(buff, p, h);
}


/*
** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
** invariant
*/
void luaE_setdebt (global_State *g, l_mem debt) {
	g->totalbytes -= (debt - g->GCdebt);
	g->GCdebt = debt;
}


CallInfo *luaE_extendCI (lua_State *L) {
	CallInfo *ci = luaM_new(L, CallInfo);
	lua_assert(L->ci->next == NULL);
	L->ci->next = ci;
	ci->previous = L->ci;
	ci->next = NULL;
	return ci;
}


void luaE_freeCI (lua_State *L) {
	CallInfo *ci = L->ci;
	CallInfo *next = ci->next;
	ci->next = NULL;
	while ((ci = next) != NULL) {
		next = ci->next;
		luaM_free(L, ci);
	}
}


static void stack_init (lua_State *L1, lua_State *L) {
	int i; CallInfo *ci;
	/* initialize stack array */
	L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, TValue);
	L1->stacksize = BASIC_STACK_SIZE;
	for (i = 0; i < BASIC_STACK_SIZE; i++)
		setnilvalue(L1->stack + i);  /* erase new stack */
	L1->top = L1->stack;
	L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
	/* initialize first ci */
	ci = &L1->base_ci;
	ci->next = ci->previous = NULL;
	ci->callstatus = 0;
	ci->func = L1->top;
	setnilvalue(L1->top++);  /* 'function' entry for this 'ci' */
	ci->top = L1->top + LUA_MINSTACK;
	L1->ci = ci;
}


static void freestack (lua_State *L) {
	if (L->stack == NULL)
		return;  /* stack not completely built yet */
	L->ci = &L->base_ci;  /* free the entire 'ci' list */
	luaE_freeCI(L);
	luaM_freearray(L, L->stack, L->stacksize);  /* free stack array */
}


/*
** Create registry table and its predefined values
*/
static void init_registry (lua_State *L, global_State *g) {
	TValue mt;
	/* create registry */
	Table *registry = luaH_new(L);
	sethvalue(L, &g->l_registry, registry);
	luaH_resize(L, registry, LUA_RIDX_LAST, 0);
	/* registry[LUA_RIDX_MAINTHREAD] = L */
	setthvalue(L, &mt, L);
	luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &mt);
	/* registry[LUA_RIDX_GLOBALS] = table of globals */
	sethvalue(L, &mt, luaH_new(L));
	luaH_setint(L, registry, LUA_RIDX_GLOBALS, &mt);
}


/*
** open parts of the state that may cause memory-allocation errors
*/
static void f_luaopen (lua_State *L, void *ud) {
	global_State *g = G(L);
	UNUSED(ud);
	stack_init(L, L);  /* init stack */
	init_registry(L, g);
	luaS_resize(L, MINSTRTABSIZE);  /* initial size of string table */
	luaT_init(L);
	luaX_init(L);
	/* pre-create memory-error message */
	g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
	luaS_fix(g->memerrmsg);  /* it should never be collected */
	g->gcrunning = 1;  /* allow gc */
}


/*
** preinitialize a state with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_state (lua_State *L, global_State *g) {
	G(L) = g;
	L->stack = NULL;
	L->ci = NULL;
	L->stacksize = 0;
	L->errorJmp = NULL;
	L->nCcalls = 0;
	L->hook = NULL;
	L->hookmask = 0;
	L->basehookcount = 0;
	L->allowhook = 1;
	resethookcount(L);
	L->openupval = NULL;
	L->nny = 1;
	L->status = LUA_OK;
	L->errfunc = 0;
}


static void close_state (lua_State *L) {
	global_State *g = G(L);
	luaF_close(L, L->stack);  /* close all upvalues for this thread */
	luaC_freeallobjects(L);  /* collect all objects */
	luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
	luaZ_freebuffer(L, &g->buff);
	freestack(L);
	lua_assert(gettotalbytes(g) == sizeof(LG));
	(*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
}


LUA_API lua_State *lua_newthread (lua_State *L) {
	lua_State *L1;
	lua_lock(L);
	luaC_checkGC(L);
	L1 = &luaC_newobj(L, LUA_TTHREAD, sizeof(LX), NULL, offsetof(LX, l))->th;
	setthvalue(L, L->top, L1);
	api_incr_top(L);
	preinit_state(L1, G(L));
	L1->hookmask = L->hookmask;
	L1->basehookcount = L->basehookcount;
	L1->hook = L->hook;
	resethookcount(L1);
	luai_userstatethread(L, L1);
	stack_init(L1, L);  /* init stack */
	lua_unlock(L);
	return L1;
}


void luaE_freethread (lua_State *L, lua_State *L1) {
	LX *l = fromstate(L1);
	luaF_close(L1, L1->stack);  /* close all upvalues for this thread */
	lua_assert(L1->openupval == NULL);
	luai_userstatefree(L, L1);
	freestack(L1);
	luaM_free(L, l);
}


LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
	int i;
	lua_State *L;
	global_State *g;
	LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
	if (l == NULL) return NULL;
	L = &l->l.l;
	g = &l->g;
	L->next = NULL;
	L->tt = LUA_TTHREAD;
	g->currentwhite = bit2mask(WHITE0BIT, FIXEDBIT);
	L->marked = luaC_white(g);
	g->gckind = KGC_NORMAL;
	preinit_state(L, g);
	g->frealloc = f;
	g->ud = ud;
	g->mainthread = L;
	g->seed = makeseed(L);
	g->uvhead.u.l.prev = &g->uvhead;
	g->uvhead.u.l.next = &g->uvhead;
	g->gcrunning = 0;  /* no GC while building state */
	g->GCestimate = 0;
	g->strt.size = 0;
	g->strt.nuse = 0;
	g->strt.hash = NULL;
	setnilvalue(&g->l_registry);
	luaZ_initbuffer(L, &g->buff);
	g->panic = NULL;
	g->version = lua_version(NULL);
	g->gcstate = GCSpause;
	g->allgc = NULL;
	g->finobj = NULL;
	g->tobefnz = NULL;
	g->sweepgc = g->sweepfin = NULL;
	g->gray = g->grayagain = NULL;
	g->weak = g->ephemeron = g->allweak = NULL;
	g->totalbytes = sizeof(LG);
	g->GCdebt = 0;
	g->gcpause = LUAI_GCPAUSE;
	g->gcmajorinc = LUAI_GCMAJOR;
	g->gcstepmul = LUAI_GCMUL;
	for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
	if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
		/* memory allocation error: free partial state */
		close_state(L);
		L = NULL;
	}
	else
		luai_userstateopen(L);
	return L;
}


LUA_API void lua_close (lua_State *L) {
	L = G(L)->mainthread;  /* only the main thread can be closed */
	lua_lock(L);
	luai_userstateclose(L);
	close_state(L);
}


